We propose a case-control study of cutaneous malignant melanoma. The objective of this study is to examine the association of malignant melanoma and a variety of putative antecedent risk factors including residential history, ethnicity, medical history, drug history, occupational history, life style, diet, family history, skin color, recreational and occupational sun exposure, hormonal factors, and habits of protection against the sun. Cases will be identified over 4 1/2 years by the LAC/USC Cancer Surveillance Program, a large, population based tumor registry providing indentification of newly diagnosed cancer cases among the large and varied population of Los Angeles County. The population at risk includes over 5 million white non-Spanish surnamed residents, and is in a southern latitude, yields about 5% of the melanoma cases in the country. The primary source of case selection will be hospital pathology files. Hematology, cytology, and autopsy reports, surgical pathology records and independent laboratory files are periodically searched for all microscopically diagnosed melanomas. Slides from each case will be requested and confirmed by independent pathology readings. Neighborhood residents of the same age, sex, and race will be used as controls. A detailed, pretested questionnaire will be administered by personal interview to each case and control. Skin, hair and eye color will be objectively classified.